Merge branch 'docs-add-configure-pull-api' into 'master'

Add in docs how to configure pull mirroring via API

See merge request gitlab-org/gitlab!47492

doc/api/projects.md

@@ -2417,6 +2417,18 @@ Read more in the [Project import/export](project_import_export.md) documentation
 
 Read more in the [Project members](members.md) documentation.
 
+## Configure pull mirroring for a project **(STARTER)**
+
+> Introduced in [GitLab Starter](https://about.gitlab.com/pricing/) 11.2.
+
+Configure pull mirroring while [creating a new project](#create-project) or [updating an existing project](#edit-project) using the API if the remote repository is publicly accessible or via `username/password` authentication. In case your HTTP repository is not publicly accessible, you can add the authentication information to the URL: `https://username:password@gitlab.company.com/group/project.git`, where password is a [personal access token](../user/profile/personal_access_tokens.md) with the API scope enabled.
+
+The relevant API parameters to update are:
+
+- `import_url`: URL of remote repository being mirrored (with `username:password` if needed).
+- `mirror`: Enables pull mirroring on project when set to `true`.
+- `only_mirror_protected_branches`: Set to `true` for protected branches.
+
 ## Start the pull mirroring process for a Project **(STARTER)**
 
 > Introduced in [GitLab Starter](https://about.gitlab.com/pricing/) 10.3.